The worldwide decline in vitamin intake is contributing to the increase in the number of overweight people. Scientists at the French research institutes INSERM and INRA draw this conclusion from an animal study in which they gave mice half of the amount of vitamins that the animals require. Thanks a lot, food industry.

Not enough
Some years ago scientists Balz Frei, Walter Willett and Bruce Ames warned against the negative way in which the mass media and scientists portray nutritional supplements with added vitamins and minerals. [nutraingredients-usa.com 03-Jun-2014]

It is so that studies have occasionally found that heavy users of these supplements have a slightly higher risk of developing cancer or cardiovascular disease. But statistics show that large groups of people in modern societies are getting far fewer minerals and vitamins than textbooks recommend.

Ninety percent of Americans consume too little vitamin D and vitamin E; sixty percent get too little magnesium, and fifty percent don't consume the recommended amount of calcium and vitamin A. And that's just a few examples. Multi-vitamins are a cheap and simple way of compensating for these deficiencies.

Overweight
One of the things that vitamins do is to help convert nutrients into energy, and French researchers wondered whether a diet with too few vitamins might encourage overweight. They conducted an experiment with mice, giving them half of the amount of vitamins usually contained in their food for a period of 12 weeks.

And indeed, although the animals' energy intake didn't increase as a result of the vitamin shortage, they did become fatter.

The vitamin shortage made the cells less sensitive to insulin, and reduced the amount of the fat sensor PPAR-alpha synthesised in the liver – and thus also reduced the fat burning.

The researchers also observed evidence of the reduced fat burning in the mice's blood. The vitamin shortage reduced the concentration of the ketone beta-hydroxybutyrate, a substance released when fatty acids are burned.

Conclusion
"Our study in mice suggests a role for vitamin insufficiency in obesity, although extensive further work is still required", the researchers write. "Vitamin deficiency based on consumption of inexpensive but vitamin-poor foods may play a role in body weight and adiposity management."

"Our study contributes to the recommendation of a healthy diet composed of diverse food products with high vitamin density, such fruit and vegetables, whole-grain cereals and fish products."